InterviewSolution
Saved Bookmarks
| 1. |
(11 + 12 + 13 + ... + 20) = ? |
| Answer» (112 + 122 + 132 + ... + 202) = (12 + 22 + 32 + ... + 202) - (12 + 22 + 32 + ... + 102) Ref: (12 + 22 + 32 + ... + n2) = 1 n(n + 1)(2n + 1) 6 = 20 x 21 x 41 - 10 x 11 x 21 6 6 = (2870 - 385) = 2485. | |